The present invention relates to boat stabilizers that are attachable to the lower drive unit of a boat motor to provide lift to the stern of the boat and otherwise improve the performance of the boat. The invention also relates to boat motors having a boat stabilizer attached thereto, methods of attaching a boat stabilizer to the lower drive unit of a boat motor and methods of manufacturing boat stabilizers.
It is known that the stability, performance, fuel efficiency and safety of certain types of boats (for example, ski boats, bass boats, pontoon boats and the like) can be improved by the addition of an after-market boat stabilizer to the lower drive unit of the boat motor. Such boat stabilizers, often referred to as hydrofoil stabilizers or hydrofoils, are typically designed to fit around the rear of the drive unit over or under the anti-cavitation plate thereof. The boat stabilizers are bolted on to the anti-cavitation plate. Examples are shown by U.S. Pat. Nos. Des. 308,851 (issued Jun. 26, 1990), 5,048,449 (issued Sep. 17, 1991), 5,107,786 (issued Apr. 28, 1992) and Des. 351,129 (issued Oct. 4, 1994), all assigned to the assignee of the present application.
A problem inherent in the after-market boat stabilizers used heretofore is that they are bolted directly on to the anti-cavitation plate of the boat motor. This requires that holes (typically 4 or more) be drilled through the anti-cavitation plate. Many boat owners simply do not want to permanently modify the structure of their lower drive units in this manner. Furthermore, drilling the holes in the precise location needed can be difficult. The boat stabilizer needs to be installed in a position that is perpendicular to the longitudinal axis of the engine and in a manner that does not leave any gaps or spaces between the boat stabilizer and the anti-cavitation plate. Gaps and open spaces between the boat stabilizer and anti-cavitation plate can hold water which creates unnecessary drag. In addition, drilling holes in the anti-cavitation plate can void the engine manufacturer's anti-corrosion protection warranty on new engines.
Another problem associated with the boat stabilizers currently available is that the stabilizers do not sufficiently harness the thrust energy generated by rotation of the boat motor propeller. Rotation of the propeller pushes water to the rear, thereby propelling the boat forward. Unfortunately, a great deal of the thrust energy created by the boat motor is lost. Rotation of the propeller imparts a substantially outward, radial force to the water. As the outward, radial force is uniform and symmetric, the associated force vectors tend to cancel out. Only the rearward component of the generated water column, referred to the “thrust cone,” imparts forward thrust to the boat. The diameter of the thrust cone increases with the length of the thrust cone. As a result, some of the water in the thrust cone ultimately is thrown above the surface and into the air, which causes the thrust energy associated therewith to be released and lost. The thrust cone associated with many boats, even when an existing boat stabilizer is utilized, reaches the surface too quickly. For example, boats that create large “rooster tails” are not operating very efficiently.
Yet another problem associated with many existing boat stabilizers is stabilizer drag. Drag is the result of friction generated by water flowing over the stabilizer as the stabilizer traverses through the water. The faster the product traverses through the water the greater the drag. Many boat stabilizers on the market do not sufficiently address the problem of drag.
Finally, the overall appearance and look of many boat stabilizers rapidly diminishes upon use of the stabilizers. Boat stabilizers are typically molded out of a polymer material by an injection molding process. The molten material is caused to swirl in the mold which results in flow or knit marks in the finished product. In an attempt to improve the aesthetics of the boat stabilizer, many manufacturers place decals (including brand names and logos and/or other decorative elements) on the top surface of the stabilizer. The decals cover up the flow or knit marks on the top surface of the stabilizer. Unfortunately, due to debris in the water and other factors, the decals get beat up and wear out fairly quickly. Even when decals are not used, the top surface of the stabilizer can become worn looking in a relatively short amount of time.
By the present invention, a boat stabilizer has been developed that overcomes the aforementioned problems. The inventive boat stabilizer can be attached to the lower drive unit of a boat motor without permanently modifying the structure of the boat motor. The shape and size of the inventive boat stabilizer causes the stabilizer to effectively harness and control the thrust energy generated by the propeller resulting in greatly improved thrust and fuel efficiency. Due to various features, the drag associated with the inventive boat stabilizer is kept to a minimum. Finally, decals and other decorative elements are integrally embedded into the top surface of the inventive boat stabilizer using in-mold decoration (“IMD”) technology which makes the elements resistant to ultraviolet light, virtually indestructible and highly appealing.